Thousands of women report period disruption after jabs but changes ‘short-lived’

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More than 30,000 women in Britain have reported disruption to their periods after Covid-19 vaccination, but the changes are “short-lived”, according to an article in a leading medical journal.

Most women return to normal after a single cycle, according to the article in The BMJ.

The opinion piece written by Dr Victoria Male, lecturer in reproductive immunology, said there was no evidence that vaccination affected fertility.

But Dr Male said that more research was needed to ensure the success of the vaccination programme.

She said that vaccine hesitancy among women was largely driven by “false claims that vaccination could harm their chances of future pregnancy”.

“Failing to thoroughly investigate reports of menstrual changes after vaccination is likely to fuel these fears,” she wrote.

“If a link between vaccination and menstrual changes is confirmed, this information will allow people to plan for potentially altered cycles.

“Clear and trusted information is particularly important for those who rely on being able to predict their menstrual cycles to either achieve or avoid pregnancy.”

She said common side effects from Covid-19 vaccination listed by the UK medical regulator – the Medicines and Healthcare products Regulatory Agency (MHRA) – included sore arm, fever, fatigue and muscle aches and pain.

Changes to periods were not listed.

“But primary care clinicians and those working in reproductive health are increasingly approached by people who have experienced these events shortly after vaccination,” she added.

“More than 30, 000 reports of these events had been made to MHRA’s yellow card surveillance scheme.”

Dr Male continued: “MHRA states that evaluation of yellow card reports does not support a link between changes to menstrual periods and Covid-19 vaccines since the number of reports is low relative to both the number of people vaccinated and the prevalence of menstrual disorders generally.

“However, the way in which yellow card data are collected makes firm conclusions difficult.”

She added: “Most people who report a change to their period after vaccination find that it returns to normal the following cycle and, importantly, there is no evidence that Covid-19 vaccination adversely affects fertility.”

The lecturer at Imperial College London said menstrual changes had been reported among women who had received both mRNA vaccines – such as the Pfizer and Moderna jabs – and adenovirus vectored Covid-19 vaccines, such as AstraZeneca.

She said that if there was a connection between vaccines and disrupted periods “it is likely to be a result of the immune response to vaccination rather than a specific vaccine component”.

Dr Male concluded: “Although reported changes to the menstrual cycle after vaccination are short-lived, robust research into this possible adverse reaction remains critical to the overall success of the vaccination programme.”

Research would also help understand any potential mechanism behind the potential link, she added.

Dr Jo Mountfield, vice president of the Royal College of Obstetricians and Gynaecologists, said: “We understand that any changes to periods following a Covid-19 vaccine can be concerning.

“We want to reassure women that any changes generally revert back to normal after one or two cycles.

“We would encourage anyone who experiences heavy bleeding that is unusual for them, especially after the menopause, to speak to a healthcare professional.

“There is no evidence to suggest that these temporary changes will have any impact on a person’s future fertility or their ability to have children.

“It is important to get vaccinated as the best protection against coronavirus. This is especially important if you are planning a pregnancy, as we know unvaccinated pregnant women are more at risk of becoming seriously ill from Covid-19.

“We support calls for more research to understand why women may be experiencing changes to their menstrual cycle after having the vaccine.”

The Medicines and Healthcare products Regulatory Agency (MHRA) said period problems can be caused by stressful life events and added that changes to the menstrual cycle have also been reported after people have had the virus or are suffering with long Covid.

Dr Alison Cave, chief safety officer at the MHRA, said they are “closely monitoring reports of suspected menstrual disorders” through the “robust” yellow card scheme.

She said: “As outlined in our vaccine safety surveillance strategy, the Yellow Card scheme is one of several sources of evidence we use when evaluating the safety of vaccines.

“Based on our current rigorous safety monitoring, women can be reassured that the current evidence does not show a link with any changes in women’s periods or symptoms, nor is there any evidence to suggest that Covid-19 vaccines will affect fertility. This is also the conclusion of our expert scientific advisory committee, the Commission on Human Medicines.

“Whilst uncomfortable or distressing, period problems are extremely common and stressful life events can disrupt women’s periods. Changes to the menstrual cycle have also been reported following infection with Covid-19 and in women affected by long-Covid.

“Our advice remains that the benefits of vaccination outweigh the risks for most people.”

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